1. Field of the Invention
This invention relates to an electro-optical device such as a television receiver and a driving method therefor in which an image or picture is formed on the basis of video signals which are transmitted from a television broadcasting station on earth, a satellite broadcasting station, a community antenna television system (CATV) station, or an individually-disposed recording device for a television picture (e.g., a video deck, a laser disk, a photoelectro-magnetic disk, etc.), and particularly to an image display device such as a television receiver and an image display method therefor in which an original image (picture) is substantially amplified to form an image with high contrast ratio and brightness even in a wide screen.
2. Description of Related Art
An image display system such as a Braun tube or a cathode-ray tube (CRT) in which an electron beam is irradiated to a phosphor screen in accordance with a video signal in a vacuum tube to induce the emission of the phosphor screen, has been conventionally utilized as a display device for displaying an image or picture on the basis of video signals which are transmitted from a television broadcasting station on earth, a satellite broadcasting station, a community antenna television system (CATV) station, or an individually-disposed recording device for a television image (e.g., a video deck, a laser disk, a photoelectro-magnetic disk, etc.). At the initial stage, a display device having a screen of 12 to 14 inches of width across corners thereof (hereinafter referred to as "12 to 14-inch wide screen") had mainly propagated. However, a display device having a 20-inch to 30 or more inch wide screen is now in the market to satisfy the recent requirement.
The display device having the 30-inch wide screen is approximately 30 inches in depth, and glass material constituting the screen thereof is designed so as to have thickness above 1 inch to keep its strength.
As another type of display device has been proposed a display system having a high-brightness Braun tube in which an image (picture) on the Braun tube is enlarged through an optical system and then displayed on a screen. This type of display system has been used for a display device having a large display (projection) area.
In a television receiver using a Braun tube, the total weight thereof exceeds 100 kg when the display screen thereof exceeds 30 inches in width across corners. When such a television receiver of 100 kg or more in weight is placed on a general home, the place position of the television receiver on the home is restricted because of its weight, and it is also difficult to move the television receiver by human power when alteration of layout of the television receiver is required. This inconvenience of the television receiver has obstructed the propagation of a large-size television receiver into the general home.
In order to avoid the above disadvantage due to the weight of the television receiver, a projection type television receiver has been proposed. However, an original high-brightness Braun tube which has been generally used in the projection type television receiver also has restriction in improvement of its brightness, and the brightness of an enlarged image (picture) itself is very low, so that the screen of this type television receiver is dark. In addition, since an image (picture) is enlarged by the optical system, the contrast ratio is high for a front-side view, however, it is still lower for a slant-side view in this projection system than in the Braun tube system. Although many kinds of projection type television receivers adopting a TFT panel are also produced, the yield of this type of television receiver in manufacture can not be improved because a manufacturing process thereof is complicated, and thus the commercial success has not yet obtained for this type television receiver.
Further, a color liquid crystal projection type of television receiver has been also developed. However, since this type of television receiver requires as a display body three or more active matrix type liquid crystal display devices having complicated wiring patterns, the yield thereof is still lower. Therefore, this type television receiver has a critical problem that the manufacturing cost is increased.